1. Field of the Invention
The present invention relates to electrophotographic transfer paper having excellent running properties when used in a high temperature and high humidity environment on full-color or monochromatic copying machines and printers using an indirect dry electrophotographic system.
2. Description of the Related Art
Accompanying with the development of color copying machines and printers as well as digitalization of these systems, high definition of an electrophotographic copying machine and printers have been investigating. In particular, digitalization of input/output information has advanced for obtaining a high quality image with a full-color electrophotographic copying machine or printer and brought about great improvements in image input, image processing, development, transfer, fixing, and the like. Developers and photoreceptors have also been improved in conformity with the tendencies of digitalization, high definition, and high color development recording.
Conventional transfer paper which has been used in monochromatic copying machines and printers according to an indirect dry electrophotographic system is not suitable for use in the above-mentioned advanced electrophotographic full-color copying machines or printers. That is, a color image formed on the conventional transfer paper suffers from unevenness of gloss or density, and transfer deficiency occurs. In order to overcome these problems, various types of coated paper have been proposed, e.g., in Unexamined Japanese Patent Publication Nos. Sho-62-198876, Sho-62-198877, Hei-3-242654, Hei-3-294600, and Hei-4-291351.
A coating layer provided for improvement of image quality causes slip on a feed roll due to its smoothness or running troubles due to lack of stiffness (bulkiness). These disadvantages can be eliminated by controlling the characteristics of base paper, using a non-film-forming resin as a coating layer, and controlling the characteristics of transfer paper so that the final product may have an air permeability of 4000 seconds or less and a water content of 4 to 6% thereby to improve both image quality and running properties, as described in Unexamined Japanese Patent Publication No. Hei-5-241366.
Although various studies have been directed to improvement in image quality of coated transfer paper, sufficient study has not been given to running properties of coated transfer paper, still less the running properties in a high temperature and high humidity condition or a low temperature and low humidity condition.
It has turned out that the coated transfer paper, though satisfactory in an ordinary environment, involves great and hitherto unknown problems in terms of running properties with change of the environment of use.
The coated transfer paper has no problem under a normal environment condition. However, under a high temperature/humidity condition, if package is opened on use and the transfer paper taken out is set on a paper feed tray so as to be fed into a machine, multiple feed in which two or more sheets of paper are fed at one time or miss-feeding in which no paper is fed occurs frequently from the just beginning of copying or printing. It has been recognized that the coated transfer paper has a large problem regarding to the running properties which was not known conventionally. Further, under a low temperature/humidity condition, even if paper is fed normally, the paper may stop in the machine on its running way. Accordingly, various problems occur accompanying with change of using environment of paper.
It is an object of the present invention to provide electrophotographic transfer paper which has a good image quality and an excellent running property particularly under high humidity condition, even when it is used on a full-color or monochromatic copying machine or printer.
Electrophotographic transfer paper is comprised of base paper and a coating layer including a pigment and a binder, said coating layer being provided on at least one side of said base paper; wherein said transfer paper has an air permeability in a range of 10 to 90 seconds, as measured according to JIS P8117 after the pretreatment specified in JIS P8111, and a coefficient of paper-to-paper friction in a range of 0.5 to 0.9 at 28xc2x0 C. and 85% RH.
Accordingly, the present invention provides transfer paper for electrophotography which exhibits satisfactory running properties on full-color or monochromatic recording equipment of indirect electrophotographic system irrespective of the environment of use and provides a satisfactory image.